Aminoplast resin photochromic coating composition and photochromic articles

ABSTRACT

Described are articles having an aminoplast resin photochromic coating prepared from an aminoplast resin, component(s) having at least two different functional groups and photochromic substances. The coatings exhibit a Fischer microhardness of from 45 to 180 Newtons per mm 2  and desirable photochromic properties, i.e., the formation of darker activated colors and faster rates of photochromic activation and fade when irradiated with ultraviolet light. Also described are photochromic aminoplast resin articles.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to provisional Application Ser. No.60/112,794, filed Dec. 18, 1998.

DESCRIPTION OF THE INVENTION

The present invention relates to coatings comprising an aminoplastresin, component(s) having at least two different functional groups andphotochromic substance(s), hereinafter referred to as photochromicaminoplast resin coatings. In particular, this invention relates toarticles coated with such photochromic coatings and photochromicarticles, i.e., polymerizates, made from such polymerizablecompositions. More particularly, this invention relates to certainphotochromic aminoplast resin coatings which when present on a substrateand exposed to activating light radiation exhibit improved photochromicproperties. Further, this invention relates to photochromic aminoplastresin coatings that meet commercially acceptable “cosmetic” standardsfor optical coatings applied to optical elements, e.g., lenses.

Photochromic compounds exhibit a reversible change in color when exposedto light radiation involving ultraviolet rays, such as the ultravioletradiation in sunlight or the light of a mercury lamp. Various classes ofphotochromic compounds have been synthesized and suggested for use inapplications in which a sunlight-induced reversible color change ordarkening is desired. The most widely described classes of photochromiccompounds are oxazines, pyrans and fulgides.

The use of melamine resins as a potential matrix for photochromiccompounds in multilayered articles has been disclosed in U.S. Pat. No.4,756,973 and Japanese patent applications 62-226134, 3-2864, 3-35236and 61-268788. In U.S. Pat. No. 4,756,973 and JP 62-226134, melamineresin is referred to in a list of several different materials, butspecific examples of melamines and reactants to produce photochromiccoatings are not disclosed. JP 61-268788, 3-2864 and 3-35236 disclosethe reaction of a melamine resin with an acrylic resin having a hydroxylgroup, a hydroxyl or carboxyl, and a hydroxyl and carboxyl groups,respectively.

It has now been discovered that photochromic aminoplast resin coatingsthat demonstrate good photochromic properties, i.e., color and fade atacceptable rates and achieve a sufficiently dark colored state, and thatmeet optical coating “cosmetic” standards may be produced. Such coatingsenable the production of photochromic articles using plastics in whichphotochromic compounds do not function properly, and avoids the use ofthermal transfer processes.

The novel coatings described herein exhibit a Fischer microhardness offrom at least 45 to 180 Newtons per mm². Articles of the presentinvention having this range of hardness are suitable for manipulation byautomated process equipment without being damaged. The photochromicaminoplast coating composition used to form the photochromic coating mayalso be used to form a photochromic aminoplast resin polymerizate.

DETAILED DESCRIPTION OF THE INVENTION

In recent years, photochromic articles, particularly photochromicplastic materials for optical applications, have been the subject ofconsiderable attention. In particular, photochromic ophthalmic plasticlenses have been investigated because of the weight advantage theyoffer, vis-à-vis, glass lenses. Moreover, photochromic transparenciesfor vehicles, such as cars and airplanes, have been of interest becauseof the potential safety features that such transparencies offer.Photochromic articles that are most useful are those in which thephotochromic compounds associated with the article exhibit a highactivated intensity and acceptable coloration and fade rates.

The use of photochromic coatings enables the preparation of photochromicplastic articles without the need to incorporate the photochromiccompound(s) into the plastic substrate which avoids the need to developspecial optical resin materials for use with photochromic compounds.This is advantageous when the plastic, e.g., thermoplasticpolycarbonate, does not have enough internal free volume or polymerchain flexibility for the photochromic compounds incorporated into theplastic to function properly. The coating composition of the presentinvention enables preparation of photochromic articles using suchplastics. Further, use of photochromic coatings result in more efficientutilization of photochromic compounds by avoiding the losses associatedwith more conventional transfer methods, e.g., imbibition or permeation,to produce photochromic articles.

Other than in the operating examples, or where otherwise indicated, allvalues, such as those expressing wavelengths, quantities of ingredients,ranges or reaction conditions, used in this description and theaccompanying claims are to be understood as modified in all instances bythe term “about”.

When the coating compositions of the present invention are applied as acoating and cured, the coating exhibits a Fischer microhardness of atleast of 45 Newtons per mm², preferably at least 55, more preferably atleast 60 Newtons per mm². Typically, the cured coating exhibits aFischer microhardness of not more than 180 Newtons per mm², preferablynot more than 160 and more preferably not more than 150 Newtons per mm².The Fischer microhardness of the coating may range between anycombination of these values, inclusive of the recited range.

The photochromic properties of the cured coating of the presentinvention are characterized by a ΔOD after 30 seconds of at least 0.15,preferably at least 0.16 and most preferably at least 0.17, and a ΔODafter 8 minutes of at least 0.47, preferably 0.50, and most preferablyat least 0.55. The photochromic properties are also characterized by ableach rate of not more than 180 seconds, preferably not more than 150,and more preferably not more than 100 seconds—all as measured at 85° F.(29° C.), and as described in Part D of Example 12 herein.

Aminoplast resin coatings having microhardness and photochromicperformance properties within the aforestated ranges can be produced bybalancing the amounts of the components of the crosslinkable compositionused to prepare the coating matrix. For example, the specific propertiesof the components comprising the coating matrix or polymerizate thatwill effect the microhardness and photochromic performance properties ofthe aminoplast resin matrix are the glass transition temperature andmolecular weight of the components, and the crosslink density of theresultant matrix. Generally, using components having higher glasstransition temperatures and molecular weights results in coatings andpolymerizates having an increased microhardness and vice versa. Anincrease in the number of reactive groups of a component will also causean increase in the microhardness, provided that all of the groups arereacted. In the latter case, the increase in the number of reactivegroups, i.e., crosslinking sites, increases the density of the curedcoating. It is believed however that the harder the coating orpolymerizate the slower the performance of the photochromic compoundcontained therein.

The contribution of a particular component, e.g., a hydroxyl-functionalcomponent such as an organic polyol, to either the hardness or softnessof the coating can be readily determined by measuring the Fischermicrohardness of the resulting aminoplast resin coating. Thehardness-producing component, as defined herein, is a component thatincreases the microhardness of the aminoplast resin coating as itsconcentration increases. Similarly, the softness-producing component, asdefined herein, is a component that decreases the microhardness of theaminoplast resin coating as its concentration increases. Examples ofhardness-producing organic polyols include, but are not limited to, lowmolecular weight polyols, amide-containing polyols, polyhydric polyvinylalcohols, e.g., poly(vinylphenol), epoxy polyols and polyacrylicpolyols. Softness-producing organic polyols include, but are not limitedto, polyester polyols, urethane polyols, and polyether polyols, e.g.,polyoxyalkylenes and poly(oxytetramethylene)diols. All of theaforementioned polyols are defined hereinafter.

The photochromic coating composition of the present invention may beprepared by combining a photochromic component with the reaction productof component(s) having at least two different functional groups selectedfrom hydroxyl, carbamate, urea or mixtures of such functional groups andan aminoplast resin, i.e., crosslinking agent. The coating compositionmay further include catalyst.

Solvents may also be present in the coating composition. However, asdescribed herein, solvents are not factored into the weight ratios andweight percents stated herein. All weight ratios and weight percentsused herein are based on the total solids in the coating composition,unless stated otherwise.

Typically, the component(s) having a plurality of functional groups ofthe present invention is a film forming polymer, but a component whichis not a film forming polymer may be utilized. However, it is necessarythat at least the combination of the aminoplast resin component with thecomponent(s) having a plurality of functional groups results in acrosslinked polymeric coating.

The component(s) having a plurality of pendant and/or terminalfunctional groups may have at least two groups selected from:

a. hydroxyl;

b. carbamate represented by structure I or II:

wherein A is —C— or —O—, R is hydrogen or C₁-C₁₈ alkyl, preferably,C₁-C₆ alkyl, or R is bonded to A and forms part of a 5 or 6 memberedring, R′ is C₁-C₁₈ alkyl;

(c) urea represented by the following structure III:

wherein B is —NH—, R″ is hydrogen or C₁-C₁₈ alkyl preferably, C₁-C₆alkyl, or R″ is bonded to B and forms part of a 5 or 6 membered ring; or

(d) mixtures of such functional groups; provided that the functionalcomponent or mixture of functional components provide at least 2different functional groups to react with the aminoplast resin.

The functional group containing component(s), hereinafter referred to asthe functional component, may be an individual material having at leasttwo different functional groups or a mixture of materials each of whichmay have two identical or different functional groups provided thatthere are at least two different functional groups present in themixture. For example, the functional component may be a combination of amaterial having two hydroxyl-functional groups and a material having twocarbamate-functional groups.

Preferably, the functional component has at least two pendant and/orterminal groups selected from hydroxyl, carbamate represented bystructure I, and urea represented by structure III, and mixturesthereof. More preferably, the functional groups are selected fromhydroxyl, carbamate represented by structure I and mixtures thereof. Thecomponent having such functional groups may be a monomer, polymer,oligomer, or mixture thereof. Preferably, the component is a polymer oroligomer such as an acrylic polymer, a polyester polymer or oligomer, apolyurethane polymer or oligomer, or a blend of two or more of thesematerials. Acrylic polymers or oligomers are preferred materials.

The acrylic materials of the functional component are copolymers of oneor more alkyl esters of acrylic acid or methacrylic acid, and,optionally, one or more other polymerizable ethylenically unsaturatedmonomers. Suitable alkyl esters of acrylic or methacrylic acids, i.e.,alkyl esters of (meth)acrylic acids, having from 1 to 17 carbon atoms inthe alkyl group, include methyl methacrylate, ethyl methacrylate, butylmethacrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate.Suitable copolymerizable ethylenically unsaturated monomers includevinyl aliphatic compounds; vinyl aromatic compounds;(meth)acrylamidobutyraldehyde dialkyl acetal monomers such asacrylamidobutyraldehyde diethyl acetal (ABDA) andmethacrylamidobutyraldehyde diethyl acetal (MABDA) monomers;poly(alkylene glycol) (meth)acrylate, e.g., methoxy polyethylene glycolmonomethacrylate; nitriles such as acrylonitrile and methacrylonitrile;vinyl and vinylidene. halides; vinyl esters; acid functional comonomerssuch as acrylic and methacrylic acid; and mixtures of such ethylenicallyunsaturated monomers. A further description of selected ethylenicallyunsaturated monomers is included hereinafter in relation to thepreparation of polyacrylic polyols.

Hydroxyl functional components may be copolymerized with the acrylicmonomers to impart hydroxyl functionality to the acrylic material.Examples of hydroxyl functional components that may be used to preparethe functional component of the present invention include, but are notlimited to, (a) low molecular weight polyols, i.e., polyols having aweight average molecular weight less than 500, e.g., aliphatic diols,such as C₂-C₁₀ aliphatic diols, triols and polyhydric alcohols; (b)polyester polyols; (c) polyether polyols; (d) amide-containing polyols;(e) polyacrylic polyols; (f) polyhydric polyvinyl alcohols; (g) epoxypolyols; (h) urethane polyols; and (i) mixtures of such polyols.Preferably, the organic polyols are selected from the group consistingof low molecular weight polyols, polyacrylic polyols, polyether polyols,polyester polyols and mixtures thereof. More preferably, the organicpolyols are selected from the group consisting of polyacrylic polyols,polyester polyols, polyether polyols, and mixtures thereof, and mostpreferably polyacrylic polyols, polyether polyols and mixtures thereof.As used herein, the term “polyol” is meant to include materials havingat least two hydroxyl groups.

Examples of low molecular weight polyols that can be used in the coatingcomposition of the present invention include: tetramethylolmethane,i.e., pentaerythritol; trimethylolethane; trimethylolpropane;di-(trimethylolpropane); dimethylolpropionic acid; 1,2-ethanediol, i.e.,ethylene glycol; 1,2-propanediol, i.e., propylene glycol;1,3-propanediol; 2,2-dimethyl-1,3-propanediol, i.e., neopentyl glycol;1,2,3-propanetriol, i.e., glycerin; 1,2-butanediol; 1,4-butanediol;1,3-butanediol; 1,2,4-butanetriol; 1,2,3,4-butanetetrol;2,2,4-trimethyl-1,3-pentanediol; 1,5-pentanediol; 2,4-pentanediol; 1,6hexanediol; 2,5-hexanediol; 1,2,6 hexanetriol; 2-methyl-1,3 pentanediol;2,4-heptanediol; 2-ethyl-1,3-hexanediol; 1,4-cyclohexanediol;1-(2,2-dimethyl-3-hydroxypropyl)-2,2-dimethyl-3-hydroxypropionate;hexahydric alcohol, i.e., sorbitol; diethylene glycol; dipropyleneglycol; 1,4-cyclohexanedimethanol; 1,2-bis(hydroxymethyl)cyclohexane;1,2-bis(hydroxyethyl)-cyclohexane; bishydroxypropyl hydantoins;TMP/epsilon-caprolactone triols; hydrogenated bisphenol A; trishydroxyethyl isocyanurate; the alkoxylation product of 1 mole of2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol-A) and 2 moles ofpropylene oxide; ethoxylated or propoxylated trimethylolpropane orpentaerythritol having a number average molecular weight less than 500,and mixtures of such low molecular weight polyols.

Polyester polyols are known and can have a number average molecularweight in the range of from 500 to 10,000. They are prepared byconventional techniques utilizing low molecular weight diols, triols andpolyhydric alcohols known in the art, including but not limited to thepreviously described low molecular weight polyols (optionally incombination with monohydric alcohols) with polycarboxylic acids.

Examples of suitable polycarboxylic acids for use in preparing thepolyester include: phthalic acid, isophthalic acid, terephthalic acid,tetrahydrophthalic acid, tetrachlorophthalic acid, hexahydrophthalicacid, methylhexahydrophthalic acid, adipic acid, azelaic acid, sebacicacid, maleic acid, succinic acid, glutaric acid, fumaric acid,chlorendic acid, trimellitic acid, tricarballylic acid and mixturesthereof. Anhydrides of the above acids, where they exist, can also beemployed. In addition, certain materials which react in a manner similarto acids to form polyester polyols are also useful Such materialsinclude lactones, e.g., caprolactonels, propiolactone and butyrolactone,and hydroxy acids such as hydroxycaproic acid and dimethylol propionicacid. If a triol or polyhydric alcohol is used, a monocarboxylic acid,such as acetic acid and/or benzoic acid, may be used in the preparationof the polyester polyols, and for some purposes, such a polyester polyolmay be desirable. Moreover, polyester polyols are understood herein toinclude polyester polyols modified with fatty acids or glyceride oils offatty acids (i.e., conventional alkyd polyols containing suchmodification). Another polyester polyol which may be utilized is oneprepared by reacting an alkylene oxide, e.g., ethylene oxide, propyleneoxide, etc., and the glycidyl esters of versaltic acid with methacrylicacid to form the corresponding ester.

Polyether polyols are known and may have a number average molecularweight in the range of from 500 to 10,000. Examples of polyether polyolsinclude various polyoxyalkylene polyols, polyalkoxylated polyols havinga number average molecular weight greater than 500, e.g.,poly(oxytetramethylene)diols and mixtures thereof. The polyoxyalkylenepolyols can be prepared, according to well-known methods, by condensingalkylene oxide, or a mixture of alkylene oxides using acid or basecatalyzed addition, with a polyhydric initiator or a mixture ofpolyhydric initiators such as ethylene glycol, propylene glycol,glycerol, sorbitol and the like. Illustrative alkylene oxides includeethylene oxide, propylene oxide, butylene oxide, e.g., 1,2-butyleneoxide, amylene oxide, aralkylene oxides, e.g., styrene oxide, and thehalogenated alkylene oxides such as trichlorobutylene oxide and soforth. The more preferred alkylene oxides include butylene oxide,propylene oxide and ethylene oxide or a mixture thereof using random orstep-wise oxyalkylation. Examples of such polyoxyalkylene polyolsinclude polyoxyethylene, i.e., polyethylene glycol, polyoxypropylene,i.e., polypropylene glycol and polyoxybutylene, i.e., polybutyleneglycol. The number average molecular of such polyoxyalkylene polyolsused as the soft segment is equal to or greater than 600, morepreferably, equal tolor greater than 725, and most preferably, equal toor greater than 1000.

The polyether polyols also include the knownpoly(oxytetramethylene)diols prepared by the polymerization oftetrahydrofuran in the presence of Lewis acid catalysts such as borontrifluoride, tin (IV) chloride and sulfonyl chloride.

The number average molecular weight of poly(oxytetramethylene)diols usedas the soft segment ranges from 500 to 5000, preferably from 650 to2900, more preferably from 1000 to 2000, and most preferably is 1000.

Polyalkoxylated polyols having a number average molecular weight greaterthan 500 may be represented by the following general formula I,

wherein m and n are each a positive number, the sum of m and n beingfrom 5 to 70, R₁ and R₂ are each hydrogen, methyl or ethyl, preferablyhydrogen or methyl and A is a divalent linking group selected from thegroup consisting of straight or branched chain alkylene (usuallycontaining from 1 to 8 carbon atoms), phenylene, C₁-C₉ alkyl substitutedphenylene and a group represented by the following general formula II,

wherein R₃ and R₄ are each C₁-C₄, alkyl, chlorine or bromine, p and qare each an integer from 0 to 4,

represents a divalent benzene group or a divalent cyclohexane group, andD is O, S, —S(O₂)—, —C(O)—, —CH2—, —CH═CH—, —C(CH₃)₂—, —C(CH₃) (C₆H₅)—or

when

is the divalent benzene group, and D is O, S, —CH₂—, or —C(CH₃)₂— when

is the divalent cyclohexane group. Preferably, the polyalkoxylatedpolyol is one wherein the sum of m and n is from 15 to 40, e.g., 25 to35, R₁ and R₂ are each hydrogen, and A is a divalent linking groupaccording to general formula II wherein

represents a divalent benzene group, p and q are each 0, and D is—C(CH₃)₂—, and most preferably, the sum of m and n is from 25 to 35,e.g., 30. Such materials may be prepared by methods which are well knownin the art. One such commonly used method involves reacting a polyol,e.g., 4,4′-isopropylidenediphenol, with an oxirane containing substance,for example ethylene oxide, propylene oxide, α-butylene oxide orβ-butylene oxide, to form what is commonly referred to as anethoxylated, propoxylated or butoxylated polyol having hydroxyfunctionality.

Examples of polyols suitable for use in preparing the polyalkoxylatedpolyols include the low molecular weight polyols described herein;phenylene diols such as ortho, meta and para dihydroxy benzene; alkylsubstituted phenylene diols such as 2,6-dihydroxytoluene,3-methylcatechol, 4-methylcatechol, 2-hydroxybenzyl alcohol,3-hydroxybenzyl alcohol, and 4-hydroxybenzyl alcohol; dihydroxybiphenylssuch as 4,4′-dihydroxybiphenyl and 2,2′-dihydroxybiphenyl; bisphenolssuch as 4,4′-isopropylidenediphenol; 4,4′-oxybisphenol;4,4′-dihydroxybenzenephenone; 4,4′-thiobisphenol; phenolphthalein;bis(4-hydroxyphenyl)methane; 4,4′-(1,2-ethenediyl)bisphenol; and4,4′-sulfonylbisphenol; halogenated bisphenols such as4,4′-isopropylidenebis(2,6-dibromophenol),4,4′-isopropylidenebis(2,6-dichlorophenol) and4,4′-isopropylidenebis(2,3,5,6-tetrachlorophenol); and biscyclohexanols,which can be prepared by hydrogenating the corresponding bisphenols,such as 4,4′-isopropylidene-biscyclohexanol; 4,4′-oxybiscyclohexanol;4,4′-thiobiscyclohexanol; and bis(4-hydroxycyclohexanol)methane.

Preferably, the polyether polyols are selected from the group consistingof polyoxyalkylene polyols, polyalkoxylated polyols,poly(oxytetramethylene)diols and mixtures thereof, and most preferably,polyoxyalkylene polyols having a number average molecular weight ofequal to or greater than 1,000, ethoxylated Bisphenol A havingapproximately 30 ethoxy groups, poly(oxytetramethylene) diols having anumber average molecular weight of 1000 and mixtures thereof.

Amide-containing polyols are known and typically are prepared from thereaction of diacids or lactones and low molecular weight polyolsdescribed herein with diamines or aminoalcohols as describedhereinafter. For example, amide-containing polyols may be prepared bythe reaction of neopentyl glycol, adipic acid and hexamethylenediamine.The amide-containing polyols may also be prepared through aminolysis bythe reaction, for example, of carboxylates, carboxylic acids, orlactones with amino alcohols. Examples of suitable diamines and aminoalcohols include hexamethylenediamines, ethylenediamines,phenylenediamine, monoethanolamine, diethanolamine, isophorone diamineand the like.

Polyhydric polyvinyl alcohols are known and can be prepared, forexample, by the polymerization of vinyl acetate in the presence ofsuitable initiators followed by hydrolysis of at least a portion of theacetate moieties. In the hydrolysis process, hydroxyl groups are formedwhich are attached directly to the polymer backbone. In addition tohomopolymers, copolymers of vinyl acetate and monomers such as vinylchloride can be prepared and hydrolyzed in similar fashion to formpolyhydric polyvinyl alcohol, polyvinyl chloride copolymers. Alsoincluded in this group are poly(vinylphenol) polymers and copolymers ofpoly(vinylphenols) which may be synthesized by vinyl polymerization ofp-vinylphenol monomers.

Epoxy polyols are known and can be prepared, for example, by thereaction of glycidyl ethers of polyphenols such as the diglycidyl etherof 2,2-bis(4-hydroxyphenyl)propane, with polyphenols suchas,2,2-bis(4-hydroxyphenyl)propane. Epoxy polyols of varying molecularweights and average hydroxyl functionality can be prepared dependingupon the ratio of starting materials used.

Urethane polyols are known and can be prepared, for example, by reactionof a polyisocyanate with excess organic polyol to form a hydroxylfunctional product. Examples of polyisocyanates useful in thepreparation of urethane polyols include toluene-2,4-diisocyanate;toluene-2,6-diisocyanate; diphenylmethane-4,′-diisocyanate; diphenylmethane-2,4′-diisocyanate; para-phenylene diisocyanate; biphenyldiisocyanate; 3,3′-dimethyl-4,4′-diphenylene diisocyanate;tetramethylene-1,4-diisocyanate; hexamethylene-1,6-diisocyanate;2,2,4-trimethyl hexane-1,6-diisocyanate; lysine methyl esterdiisocyanate; bis (isocyanato ethyl)fumarate; isophorone diisocyanate;ethylene diisocyanate; dodecane-1,12-diisocyanate;cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate;cyclohexane-1,4-diisocyanate; methyl cyclohexyl diisocyanate;dicyclohexylmethane diisocyanate; hexahydrotoluene-2,4-diisocyanate;hexahydrotoluene-2,6-diisocyanate; hexahydrophenylene-1,3-diisocyanate;hexahydrophenylene-1,4-diisocyanate; polymethylene polyphenolisocyanates perhydrodiphenylmethane-2,4′-diisocyanate;perhydrodiphenylmethane-4,4′-diisocyanate and mixtures thereof.

Examples of organic polyols useful in the preparation of urethanepolyols include hydroxyl-terminated homopolymers of butadiene, the otherpolyols described herein, e.g., low molecular weight polyols, polyesterpolyols, polyether polyols, amide-containing polyols, polyacrylicpolyols, polyhydric polyvinyl alcohols and mixtures thereof.

The polyacrylic polyols are known and can be prepared by free-radicaladdition polymerization techniques of monomers described hereinafter.Preferably said polyacrylic polyols have a weight average molecularweight of from 500 to 50,000 and a hydroxyl number of from 20 to 270.More preferably, the weight average molecular weight is from 1000 to30,000 and the hydroxyl number is from 80 to 250. Most preferably, theaverage molecular weight is from 3,000 to 20,000 and the hydroxyl numberis from 100 to 225.

Polyacrylic polyols include, but are not limited to, the knownhydroxyl-functional addition polymers and copolymers of acrylic andmethacrylic acids; their ester derivatives including, but not limitedto, their hydroxyl-functional ester derivatives. Examples ofhydroxyl-functional ethylenically unsaturated monomers to be used in thepreparation of the hydroxyl-functional addition polymers includehydroxyethyl (meth)acrylate, i.e., hydroxyethyl acrylate andhydroxyethyl methacrylate, hydroxypropyl (meth)acrylate, hydroxybutyl(meth)acrylate, hydroxymethylethyl acrylate, hydroxymethylpropylacrylate and mixtures thereof.

More preferably, the polyacrylic polyol is a copolymer ofhydroxy-functional ethylenically unsaturated (meth)acrylic monomers andother ethylenically unsaturated monomers selected from the groupconsisting of vinyl aromatic monomers, e.g., styrene, α-methyl styrene,t-butyl styrene and vinyl toluene; vinyl aliphatic monomers such asethylene, propylene and 1,3-butadiene; (meth)acrylamide;(meth)acrylonitrile; vinyl and vinylidene halides, e.g., vinyl chlorideand vinylidene chloride; vinyl esters, e.g., vinyl acetate; alkyl estersof acrylic and methacrylic acids having from 1 to 17 carbon atoms in thealkyl group, including methyl (meth)acrylate, ethyl (meth)acrylate,butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl(meth)acrylate, isobornyl (meth)acrylate and lauryl (meth)acrylate;epoxy-functional ethylenically unsaturated monomers such as glycidyl(meth)acrylate; carboxy-functional ethylenically unsaturated monomerssuch as acrylic and methacrylic acids and mixtures of such ethylenicallyunsaturated monomers.

The hydroxyl-functional ethylenically unsaturated (meth)acrylicmonomer(s) may comprise up to 95 weight percent of the polyacrylicpolyol copolymer. Preferably it comprises up to 70 weight percent, andmore preferably, the hydroxyl-functional ethylenically unsaturated(meth)acrylic monomer(s) comprises up to 45 weight percent, e.g., 40weight percent, of the total copolymer.

The polyacrylic polyols described herein can be prepared by free radicalinitiated addition polymerization of the monomer(s), and by organicsolution polymerization techniques. The monomers are typically dissolvedin an organic solvent or mixture of solvents including ketones such asmethyl ethyl ketones, esters such as butyl acetate, the acetate ofpropylene glycol, and hexyl acetate, alcohols such as ethanol andbutanol, ethers such as propylene glycol monopropyl ether andethyl-3-ethoxypropionate, and aromatic solvents such as xylene andSOLVESSO 100, a mixture of high boiling hydrocarbon solvents availablefrom Exxon Chemical Co. The solvent is first heated to reflux, usually70 to 160° C., and the monomer or a mixture of monomers and free radicalinitiator is slowly added to the refluxing solvent, over a period ofabout 1 to 7 hours. Adding the monomers too quickly may cause poorconversion or a high and rapid exothermic reaction, which is a safetyhazard. Suitable free radical initiators include t-amyl peroxyacetate,di-t-amyl peroxyacetate and 2,2′-azobis (2-methylbutanenitrile). Thefree radical initiator is typically present in the reaction mixture atfrom 1 to 10 percent, based on total weight of the monomers. The polymerprepared by the procedures described herein is non-gelled or ungelledand preferably has a weight average molecular weight of from 500 to50,000 grams per mole.

The molecular weight of suitable hydroxyl-functional components for thepreparation of compositions of the invention can vary within wide limitsdepending on the nature of the specific classes of polyols selected.Typically, the number average molecular weight of suitable polyols canrange from 62 to 50,000, preferably from 1000 to 20,000, and thehydroxyl equivalent weight can range from 31 to 25,000, preferably 500to 10,000. The molecular weights of the hydroxyl group-containingpolymers are determined by gel permeation chromatography using apolystyrene standard.

Carbamate functional groups of structure I may be incorporated aspendant groups into the acrylic polymer by copolymerizing the acrylicmonomers with a carbamate functional vinyl monomer, for example acarbamate functional alkyl ester of methacrylic acid. These carbamatefunctional alkyl esters are prepared by reacting, for example, ahydroxylalkyl carbamate, such as the reaction product of ammonia andethylene carbonate or propylene carbonate, with methacrylic anhydride.Other carbamate functional vinyl monomers are, for instance, thereaction product of hydroxyethyl methacrylate, isophorone diisocyanate,and hydroxypropyl carbamate (yielding structure I), or the reactionproduct of hydroxypropyl methacrylate, isophorone diisocyanate, andmethanol (yielding structure II). Still other carbamate functional vinylmonomers may be used, such as the reaction product of isocyanic acid(HNCO) with a hydroxyl functional acrylic or methacrylic monomer such ashydroxyethyl acrylate, and those carbamate functional vinyl monomersdescribed in U.S. Pat. No. 3,479,328. Pendant carbamate groups can alsobe incorporated into the acrylic polymer by reacting a hydroxylfunctional acrylic polymer with a low molecular weight alkyl carbamatesuch as methyl carbamate. Reference is made to Japanese Kokai 51-4124.Also, hydroxyl functional acrylic polymers can be reacted with isocyanicacid yielding pendant carbamate groups. Note that the production ofisocyanic acid is disclosed in U.S. Pat. No. 4,364,913. Likewise,hydroxyl functional acrylic polymers can be reacted with urea to give anacrylic polymer with pendant carbamate groups.

Urea groups of structure III may be incorporated as pendant groups intothe acrylic polymer by copolymerizing the acrylic monomers with ureafunctional vinyl monomers such as urea functional alkyl esters ofacrylic acid or methacrylic acid. Examples include the condensationproduct of acrylic acid or methacrylic acid with a hydroxyalkyl ethyleneurea such as hydroxyethyl ethylene urea. Other urea functional monomersare, for example, the reaction product of hydroxyethyl methacrylate,isophorone diisocyanate, and hydroxyethyl ethylene urea.

The acrylic materials, i.e., polymers, of the functional groupcontaining component may be prepared by the aforedescribed free radicalpolymerization methods disclosed in relation to polyacrylic polyols orby solution polymerization techniques in the presence of suitablecatalysts. Such catalysts are organic peroxides or azo compounds, forexample, benzoyl peroxide or N,N-azobis(isobutyronitrile). Thepolymerization may be carried out in an organic solution in which themonomers are soluble by techniques conventional in the art. Alternately,the acrylic polymer may be prepared by aqueous emulsion or dispersionpolymerization techniques well known in the art.

The acrylic polymer typically has a weight average molecular weight offrom about 500 to 50,000, preferably from about 1,000 to 30,000 asdetermined by gel permeation chromatography using a polystyrenestandard, and an equivalent weight of less than 5000, preferably withinthe range of 140 to 2500, based on equivalents of reactive pendant orterminal hydroxyl, carbamate, urea, or combinations of such functionalgroups. The equivalent weight is a calculated value based on therelative amounts of the various ingredients used in making the acrylicmaterial and is based on solids of the acrylic material.

Polyesters may also be used in the formulation of the functionalcomponent in the coating composition and may be prepared by thepolyesterification of a polycarboxylic acid or anhydride thereof withpolyols and/or an epoxide. Examples of suitable materials for preparingpolyesters are described herein in relation to polyester polyols.Polyesters having hydroxyl-functional groups may be prepared by theaforedescribed methods for making polyester polyols.

Carbamate functional groups of structure I may be incorporated aspendant groups into a polyester by first forming a hydroxylalkylcarbamate which can be reacted with the polyacids and polyols used informing the polyester. A polyester oligomer may be prepared by reactinga polycarboxylic acid such as the aforementioned with a hydroxyalkylcarbamate. An example of a hydroxylalkyl carbamate is the reactionproduct of ammonia and ethylene carbonate or propylene carbonate. Thehydroxylalkyl carbamate is condensed with acid functionality on thepolyester or polycarboxylic acid, yielding pendant carbamatefunctionality. Pendant carbamate functional groups of structure I mayalso be incorporated into the polyester by reacting isocyanic acid or alow molecular weight alkyl carbamate such as methyl carbamate with ahydroxyl functional polyester. Also, pendant carbamate functionality maybe incorporated into the polyester by reacting a hydroxy functionalpolyester with urea.

Urea groups of structure III may be incorporated into the polyester aspendant groups by reacting a hydroxyl functional urea such as ahydroxyalkyl ethylene urea with the polyacids and polyols used in makingthe polyester. A polyester oligomer can be prepared by reacting apolyacid with a hydroxyl functional urea. Also, isocyanate terminatedpolyurethane or polyester prepolymers may be reacted with primaryamines, aminoalkyl ethylene urea, or hydroxylalkyl ethylene urea toyield materials with pendant urea groups. Preparation of these polymersis known in the art and is described in U.S. Pat. No. 3,563,957.

Polyurethanes may also be used in the formulation of the functionalcomponent in the coating composition. Polyurethanes may be formed byreacting a polyisocyanate with a polyester having hydroxyl functionalityand containing pendant hydroxyl, carbamate and/or urea groups.Alternatively, the polyurethane can be prepared by reacting apolyisocyanate with a polyester polyol and a hydroxylalkyl carbamate orisocyanic acid as separate reactants. Examples of suitablepolyisocyanates are aromatic and aliphatic polyisocyanates, withaliphatic being preferred because of better color and durabilityproperties. Examples of suitable aromatic diisocyanates arediphenylmethane-4,4′-diisocyanate, 1,3-phenylene diisocyanate,1,4-phenylene diisocyanate, and toluene diisocyanate. Examples ofsuitable aliphatic diisocyanates are straight chain aliphaticdiisocyanates such as 1,4-tetramethylene diisocyanate and1,6-hexamethylene diisocyanate. Also, cycloaliphatic diisocyanates canbe employed and may be selected to impart hardness to the product.Examples include 1,4-cyclohexyl diisocyanalte, isophorone diisocyanate,alpha,alpha-xylylene diisodyanate and4,4′-methylene-bis-(cyclohexylisocyanate). Other polyisocyanates usefulin preparing the polyurethane are included in the aforedescribed methodsfor making urethane polyols.

The polyester or polyurethane materials used to prepare the functionalcomponent typically have a number average molecular weights of about 300to 3,000, preferably about 300 to 1,500 as determined by gel permeationchromatography using a polystyrene standard, and an equivalent weight offrom about 140 to 2,500 based on equivalents of pendant hydroxyl,carbamate, urea or combinations of such functional groups. Theequivalent weight is a calculated value based on the relative amounts ofthe various ingredients used in making the polyester or polyurethane andis based on solids of the material.

The aminoplast resin of the coating composition of the present inventionis in the composition in amounts of at least 1 percent by weight,preferably, at least 2 percent by weight, and more preferably, at least5 percent by weight. Typically, the aminoplast resin is present inamounts of not more than 30 percent by weight, preferably, not more than20 percent by weight and most preferably, not more than 15 percent byweight in the coating composition. The amount of aminoplast resin in thecoating composition may range between any combination of these values,inclusive of the recited values. Aminoplast resins are condensationproducts of amines or amides with aldehydes. Examples of suitable amineor amides are melamine, benzoguanamine, glycoluril, urea and similarcompounds. Preferably, the aminoplast resin has at least two reactivegroups.

Generally, the aldehyde employed is formaldehyde, although products canbe made from other aldehydes such as acetaldehyde, crotonaldehyde,benzaldehyde and furfural. The condensation products contain methylolgroups or similar alkylol groups depending on the particular aldehydeemployed. These alkylol groups may be etherified by reaction with analcohol. Various alcohols employed include monohydric alcoholscontaining from 1 to 6 carbon atoms such as methanol, ethanol,isopropanol, n-butanol, pentanol and hexanol. Preferably, alcoholscontaining from 1 to 4 carbon atoms are used.

Aminoplast resins are commercially available from American Cyanamid Co.under the trademark CYMEL and from Monsanto Chemical Co. under thetrademark RESIMENE. The preferred aminoplast resin for use in thecoating composition of the present invention is an alkylatedmelamine-formaldehyde condensate found in products such as CYMEL® 345,350 and/or 370 resins. However, condensation products of other aminesand amides can also be employed, for example, aldehyde condensates oftriazines, diazines, triazoles, guanidines, guanimines and alkyl- andaryl-substituted derivatives of such compounds, including alkyl- andaryl-substituted melamines. Some examples of such compounds areN,N′-dimethyl urea, benzourea, dicyandiamide, formaguanamine,acetoguanamine, ammeline, 2-chloro-4,6-diamino-1,3,5-triazine,6-methyl-2,4-diamino,1,3,5-traizine, 3,5-diaminotriazole,triaminopyrimidine,2-mercapto-4,6-diamino-pyrimidine,3,4,6-tris(ethylamino)-1,3,5-triazine, tris(alkoxycarbonylamino)triazineand the like.

Typically, the amount of the functional group containing component andthe aminoplast component in the coating compositions of the inventionare selected to provide a ratio of equivalents of functional groups,i.e., hydroxyl, carbamate and/or urea, to equivalents of reactiveaminoplast groups, i.e., methylol and/or methylol ether groups, in therange of 0.5 to 2:1. This ratio is based on calculated equivalentweights and is sufficient to result in a crosslinked coating. Thefunctional component and the aminoplast component in combination may bepresent in the coating composition in amounts of from 20 to 99.9,preferably from 60 to 95 percent, and more preferably from 70 to 90percent by weight based on weight of total resin solids.

The coating composition of the invention may include a catalytic agentfor accelerating the curing reaction between functional groups of thefunctional group containing component and the reactive groups of theaminoplast component. Examples of suitable catalysts are acidicmaterials and include phosphoric acid or substituted phosphoric acidssuch as alkyl acid phosphate and phenyl acid phosphate, sulfonic acidsor substituted sulfonic acids such as para-toluene sulfonic acid,dodecylbenzine sulfonic acid and dinonylnaphthalene sulfonic acid. Theamount of optional catalyst is a catalytic amount, i.e., an amountnecessary to catalyze the polymerization of monomers. The catalyst maybe present in an amount of from 0.5 to 5.0 percent by weight, preferablyfrom 1 to 2 percent by weight, based on the total weight of resinsolids. After adding a catalytic amount of catalyst, any manner ofcuring the polymerizable composition of the present invention that isappropriate for the specific composition and substrate may be used.

Solvents that may be present in the coating composition of the presentinvention are those that are necessary to dissolve the solid components.The minimum amount of solvent present in the coating composition is asolvating amount, i.e., an amount which is sufficient to solubilize thesolid components in the coating composition. For example, the amount ofsolvent present may range from 10 to 80 weight percent based on thetotal weight of the coating composition.

Suitable solvents include, but are not limited to, the following:benzene, toluene, methyl ethyl ketone, methyl isobutyl ketone, acetone,ethanol, tetrahydrofurfuryl alcohol, propyl alcohol, propylenecarbonate, N-methyl pyrrolidinone, N-vinyl pyrrolidinone, N-acetylpyrrolidinone, N-hydroxymethyl pyrrolidinone, N-butyl pyrrolidinone,N-ethyl pyrrolidinone, N-(N-octyl) pyrrolidinone, N-(N-dodecyl)pyrrolidinone, 2-methoxyethyl ether, xylene, cyclohexane, 3-methylcyclohexanone, ethyl acetate, butyl acetate, tetrahydrofuran, methanol,amyl propionate, methyl propionate, propylene glycol methyl ether,diethylene glycol monobutyl ether, dimethyl sulfoxide, dimethylforamide, ethylene glycol, mono- and dialkyl ethers of ethylene glycoland their derivatives which are sold as CELLOSOLVE industrial solventsby Union Carbide, and mixtures of such solvents.

The photochromic aminoplast resin coating composition of the presentinvention may further comprise additional conventional ingredients whichimpart desired characteristics to the composition, or which are requiredfor the process used to apply and cure the composition to the substrateor which enhance the cured coating made therefrom. Such additionalingredients comprise rheology control agents, leveling agents, e.g.,surfactants, plasticizers such as benzoate esters, initiators,cure-inhibiting agents, free radical scavengers, polymer chainterminating agents and adhesion promoting agents, such astrialkoxysilanes preferably having an alkoxy radical of 1 to 4 carbonatoms, including γ-glycidoxypropyltrimethoxysilane,γ-aminopropyltrimethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilaneand aminoethyltrimethoxysilane.

Photochromic compounds that may be utilized in the aminoplast resincoating composition(s) of the present invention are organic photochromiccompounds. Such compounds may be used individually or in combinationwith other complementary photochromic compounds. Organic photochromiccompounds or substances containing the same used in the coatingcomposition described herein have at least one activated absorptionmaxima within the range of between about 400 and 700 nanometers. Suchsubstances may be incorporated, e.g., dissolved or dispersed, in theaminoplast resin composition used to prepare the photochromic aminoplastresin coating and color when activated to an appropriate hue.

More particularly, in one embodiment the organic photochromic componentcomprises:

(a) at least one photochromic organic compound having a visible lambdamax of from 400 nanometers to 525 nanometers; and

(b) at least one photochromic organic compound having a visible lambdamax of from greater than 525 nanometers to 700 nanometers.

Examples of suitable photochromic compounds for use in the aminoplastresin coating composition of the present invention include benzopyrans,naphthopyrans, e.g., naphtho[1,2-b]pyrans and naphtho[2,1-b]pyrans,phenanthropyrans, quinopyrans, benzoxazines, naphthoxazines,spiro(indoline)pyridobenzoxazines and indeno-fused naphthopyrans such asthose disclosed in U.S. Pat. No. 5,645,767. Specific examples includethe novel naphthopyrans of U.S. Pat. No. 5,658,501 and the complementaryorganic photochromic substances disclosed in this patent from column 11,line 57 through column 13, line 36. Other photochromic substancescontemplated for use herein are photochromic metal-dithizonates, e.g.,mercury dithizonates which are described in, for example, U.S. Pat. No.3,361,706; fulgides and fulgimides, e.g. the 3-furyl and 3-thienylfulgides and fulgimides, which are described in U.S. Pat. No. 4,931,220at column 20, line 5 through column 21, line 38, and mixtures of theaforementioned suitable photochromic substances.

The disclosures relating to such photochromic compounds in theaforedescribed patents are incorporated herein, in toto, by reference.The photochromic coatings of the present invention may contain onephotochromic compound or a mixture of photochromic compounds, asdesired. Mixtures of photochromic compounds may be used to attaincertain activated colors such as a near neutral gray or brown. Furtherdiscussion of neutral colors and ways to describe such colors is foundin U.S. Pat. No. 5,645,767, column 12, line 66 to column 13, line 19.

The amount of the photochromic substances described herein to be used inthe coating or polymerizate of the present invention is an amountsufficient to produce a photochromic effect discernible to the naked eyeupon activation. Generally such amount can be described as aphotochromic amount.

The relative amounts of the aforesaid photochromic compounds used willvary and depend in part upon the relative intensities of the color ofthe activated species of such compounds, and the ultimate color desired.Generally, the amount of photochromic substance incorporated into thecoating composition may range from 0.1 to 40 weight percent based on theweight of the solids in the coating composition. Preferably, theconcentration of photochromic substances ranges from 1.0 to 30 weightpercent, more preferably, from 3 to 20 weight percent, and mostpreferably, from 5 to 15 weight percent, e.g., from 7 to 14 weightpercent.

The photochromic compound(s) described herein may be incorporated intothe coating composition by dissolving or dispersing the photochromicsubstance within a component, e.g., the organic polyol, of the coatingcomposition. The photochromic substance may be added directly to thecoating composition or it may be dissolved in solvent before adding itto the component or to the formulated coating composition.Alternatively, the photochromic compounds may be incorporated into thecured coating or polymerizate by imbibition, permeation or othertransfer methods, as is known by those skilled in the art.

Compatible (chemically and color-wise) tints, i.e., dyes, may be addedto the coating composition, applied to the coated article or applied tothe substrate prior to coating to achieve a more aesthetic result, formedical reasons, or for reasons of fashion. The particular dye selectedwill vary and depend on the aforesaid need and result to be achieved. Inone embodiment, the dye may be selected to complement the colorresulting from the activated photochromic substances, e.g., to achieve amore neutral color or absorb a particular wavelength of incident light.In another embodiment, the dye may be selected to provide a desired hueto the substrate and/or coated article when the photochromic substanceis in an unactivated state.

Adjuvant materials may also be incorporated into the coating compositionwith the photochromic substances, prior to, simultaneously with orsubsequent to application or incorporation of the photochromicsubstances in the coating composition or cured coating. For example,ultraviolet light absorbers may be admixed with photochromic substancesbefore their addition to the coating composition or such absorbers maybe superposed, e.g., superimposed, as a layer between the photochromiccoating and the incident light. Further, stabilizers may be admixed withthe photochromic substances prior to their addition to the coatingcomposition to improve the fatigue resistance of the photochromicsubstances. Stabilizers, such as hindered amine light stabilizers(HALS), antioxidants, e.g., polyphenolic antioxidants, asymmetricdiaryloxalamide (oxanilide) compounds and singlet oxygen quenchers,e.g., a nickel ion complex with an organic ligand, or mixtures ofstabilizers are contemplated. They may be used alone or in combination.Such stabilizers are described in U.S. Pat. Nos. 4,720,356, 5,391,327and 5,770,115 which patents are incorporated herein by reference.

The coating compositions of the present invention may be applied tosubstrates, of any type such as, for example paper, glass, ceramics,wood, masonry, textiles, metals and polymeric organic materials.Preferably, the substrate is a polymeric organic material, particularly,thermoset and thermoplastic polymeric organic materials, e.g.,thermoplastic polycarbonate type polymers and copolymers andhomopolymers or copolymers of a polyol(allyl carbonate) used as organicoptical materials.

The amount of the coating composition applied to the substrate is anamount necessary to incorporate a sufficient quantity of the organicphotochromic substance(s) to produce a coating that exhibits therequired change in optical density (ΔOD) when the cured coating isexposed to UV radiation. The required change in optical density is thatwhich, when tested at 85° F. (29.4° C.) produces a ΔOD of at least 0.15after 30 seconds and at least 0.47 after 8 minutes. The bleach rate ofthe photochromic coating (the photochromic(s) in the coating) should benot more than 180 seconds using the photochromic response testingdescribed in Part D of Example 12 herein. The applied coating may have athickness of at least 5 microns, preferably, at least 10 microns, morepreferably at least 20 microns, e.g., 25 microns. The applied coatingwill also usually have a thickness of not more than 200 microns,preferably, not more than 100 microns, and more preferably not more than50 microns, e.g., 40 microns. The thickness of the coating may rangebetween any combination of these values, inclusive of the recitedvalues.

It is typical to treat the surface of the substrate to be coated priorto applying the coating composition of the present invention for thepurposes of cleaning the surface and promoting adhesion. Effectivetreatment techniques for plastics, such as those prepared from CR-39®diethylene glycol bis(allyl carbonate) monomer or thermoplasticpolycarbonate, e.g., a resin derived from bisphenol A and phosgene,include ultrasonic cleaning; washing with an aqueous mixture of organicsolvent, e.g., a 50:50 mixture of isopropanol: water or ethanol: water;UV treatment; activated gas treatment, e.g., treatment with lowtemperature plasma or corona discharge, and chemical treatment such ashydroxylation, i.e., etching of the surface with an aqueous solution ofalkali, e.g., sodium hydroxide or potassium hydroxide, that may alsocontain a fluorosurfactant. See U.S. Pat. No. 3,971,872, column 3, lines13 to 25; U.S. Pat. No. 4,904,525, column 6, lines 10 to 48; and U.S.Pat. No. 5,104,692, column 13, lines 10 to 59, which describe surfacetreatments of polymeric organic materials.

The treatment used for cleaning glass surfaces will depend on the typeof dirt present on the glass surface. Such treatments are known to thoseskilled in the art. For example, washing the glass with an aqueoussolution that may contain a low foaming, easily rinsed detergent,followed by rinsing and drying with a lint-free cloth; and ultrasonicbath treatment in heated (about 50° C.) wash water, followed by rinsingand drying. Pre-cleaning with an alcohol-based cleaner or organicsolvent prior to washing may be required to remove adhesives from labelsor tapes.

In some cases, it may be necessary to apply a primer to the surface ofthe substrate before application of the coating composition of thepresent invention. The primer serves as a barrier coating to preventinteraction of the coating ingredients with the substrate and viceversa, and/or as an adhesive layer to adhere the coating composition tothe substrate. Application of the primer may be by any of the methodsused in coating technology such as, for example, spray coating, spincoating, spread coating, curtain coating, dip coating, casting orroll-coating.

The use of protective coatings, some of which may containpolymer-forming organosilanes, as primers to improve adhesion ofsubsequently applied coatings has been described. In particular, the useof non-tintable coatings is preferred. Examples of commercial coatingproducts include SILVUE124 and HI-GARD coatings, available from SDCCoatings, Inc. and PPG Industries, Inc., respectively. In addition,depending on the intended use of the coated article, it may be necessaryto apply an appropriate protective coating(s), i.e., an abrasionresistant coating onto the exposed surface of the coating composition toprevent scratches from the effects of friction and abrasion. In somecases, the primer and protective coatings are interchangeable, i.e., thesame coating may be used as the primer and the protective coating(s).Other coatings or surface treatments, e.g., a tintable coating,antireflective surface, etc., may also be applied to the cured coatingof the present invention.

The coating composition of the present invention may be applied usingthe same methods described herein for applying the primer and theprotective coating(s) or other methods known in the art can be used.Preferably, the coating composition is applied by spin coating, curtaincoating, dip coating, spray coating methods, or by methods used inpreparing overlays. Such methods for producing overlays are disclosed inU.S. Pat. No. 4,873,027, which patent is incorporated herein byreference.

Following application of the coating composition to the treated surfaceof the substrate, the coating is cured. Depending on the componentsselected for the coating composition of the present invention, thecoating may be cured at temperatures ranging from 22° C. to 200° C. Ifheating is required to obtain a cured coating, temperatures of between80° C. and a temperature above which the substrate is damaged due toheating, e.g., 80° C. to 200° C., are typically used. For example,certain organic polymeric materials may be heated up to 130° C. for aperiod of 1 to 16 hours in order to cure the coating without causingdamage to the substrate. While a range of temperatures has beendescribed for curing the coated substrate, it will be recognized bypersons skilled in the art that temperatures other than those disclosedherein may be used. Additional methods for curing the photochromicaminoplast resin coating composition include irradiating the coatingwith infrared, ultraviolet, visible, microwave, or electron radiation.This may be followed by a heating step.

Preferably, the resulting cured coating meets commercially acceptable“cosmetic” standards for optical coatings. Examples of cosmetic defectsof coated lens include an orange peel-like appearance, pits, spots,inclusions, cracks and crazing of the coating. Most preferably, thecoatings prepared using the photochromic coating composition of thepresent invention are substantially free of cosmetic defects.

Examples of polymeric organic materials that may be substrates for thecoating composition of the present invention are polymers, i.e.,homopolymers and copolymers, of the monomers and mixtures of monomersdisclosed in U.S. Pat. No. 5,658,501 from column 15, line 28 to column16, line 17, which is incorporated herein by reference.

Examples of such monomers and polymers include: polyol(allylcarbonate)monomers, e.g., diethylene glycol bis(allyl carbonate), whichmonomer is sold under the; trademark CR-39; polyol(meth)acryloylterminated carbonate monomer; diethylene glycol dimethacrylate monomers;ethoxylated phenol methacrylate monomers; diisopropenyl benzenemonomers; ethoxylated trimethylol propane triacrylate monomers; ethyleneglycol bismethacrylate monomers; poly(ethylene glycol)bis methacrylatemonomers; urethane acrylate monomers; poly(ethoxylated bisphenol Adimethacrylate); poly(vinyl acetate); poly(vinyl alcohol); poly(vinylchloride); poly(vinylidene chloride); polyurethanes, polythiourethanes,thermoplastic polycarbonates, such as the carbonate-linked resin derivedfrom bisphenol A and phosgene, which is sold under the trademark LEXAN;polyesters, such as the material sold under the trademark MYLAR;poly(ethylene terephthalate); polyvinyl butyral; and poly(methylmethacrylate), such as the material sold under the trademark PLEXIGLASand mixtures thereof.

More particularly contemplated, is the use of the combination of thephotochromic aminoplast resin coating composition of the presentinvention with polymeric organic materials such as optically clearpolymerizates, i.e., materials suitable for optical applications, suchas optical elements, e.g., plano and vision correcting ophthalmiclenses, windows, clear polymeric films, automotive transparencies, e.g.,windshields, aircraft transparencies, plastic sheeting, etc. Suchoptically clear polymerizates may have a refractive index that may rangefrom 1.48 to 2.00, e.g., from 1.495 to 1.75 or from 1.50 to 1.66.Specifically contemplated are optical elements made of thermoplasticpolycarbonates. Application of the photochromic aminoplast resin coatingcomposition of the present invention to a polymeric film in the form ofan “applique” may be accomplished using the methods describe in column17, line 28 to column 18, line 57 of U.S. Pat. No. 5,198,267.

Most particularly contemplated, is the use of the combination of thephotochromic aminoplast resin coating composition of the presentinvention with optical elements to produce photochromic opticalarticles. Such articles are prepared by sequentially applying to theoptical element a primer, the photochromic aminoplast resin compositionof the present invention and appropriate protective coating(s). Theresulting cured coating preferably meets commercially acceptable“cosmetic” standards for optical coatings, and most preferably, issubstantially free of cosmetic defects.

In another embodiment of the invention, the photochromic coatingcomposition may be used to form polymerizates, e.g., shaped solidoptically clear polymerizates, as defined herein with respect topolymeric organic materials. Polymerization of the coating compositionmay be accomplished by adding to the polymerizable composition acatalyst and curing in a manner appropriate for the specific compositionand desired shape. The resulting polymerizate may have a thickness of0.5 millimeters or more.

In one contemplated embodiment, a glass two-part lens mold is filledwith desolvated photochromic coating composition, i.e., thepolymerizable composition containing a minimal amount of solvent, whichmay additionally contain a catalytic amount of phosphoric acid. Theglass mold is sealed and placed in an oven. A thermal polymerizationcycle is initiated which may range from 10 to 20 hours duration at about45 to 110° C. Afterwards, the mold is opened and the resulting lens,i.e., polymerizate, is removed. The polymer lens thus produced is thenannealed for a period and at a temperature sufficient to eliminateresidual stresses in the lens. The temperature is generally between 100and 110° C. and annealing is carried out for 1 to 5 hours. If thephotochromic material was not included in the polymerizable composition,it may be incorporated into the polymerizate by imbibition, permeationor other transfer methods known to those skilled in the art.

In a further contemplated embodiment, a semi-finished single vision(SFSV) lens having an adherent layer of the photochromic crosslinkablecomposition of the present invention may be prepared by an overmoldingprocess. Typically, a predetermined volume of the photochromicpolymerizable composition is dispensed into a volume defined by aspherical negative glass mold, which approximately matches the frontsurface curve and the outer diameter of a SFSV lens. The glass mold isfitted with a circular polyvinyl chloride gasket that extendsapproximately 0.2 millimeters above the mold and has an inside diameterapproximately 4 millimeters less than outside diameter of the glassmold. After the monomer is dispensed, the SFSV lens is carefully placedon the dispensed polymerizable composition which spreads to fill thedefined volume. A circular glass plate having an outside diameter equalto or greater than that of the lens is placed onto the rear surface ofthe lens. A spring clamp is positioned so that one side of the clamp ison the front surface of the negative mold and other side of the clamp ison the back surface of the glass plate. The resulting assembly is sealedby taping the circumference of the plate-lens-gasket-mold usingpolyurethane tape. The assembly is preheated in an air oven from 30 to95° C. for 60 minutes and subsequently, the temperature is increasedfrom 95° C. to 125° C. and decreased to 82° C. over a 3 hour interval.The assembly is separated by inserting a wedge beneath the gasketbetween the lens and mold. The lens now has an adherent layer of from180 to 200 microns. If the photochromic material was not included in thepolymerizable composition, it may be incorporated into the adherentlayer by imbibition, permeation or other transfer methods known to thoseskilled in the art.

The present invention is more particularly described in the followingexamples, which are intended as illustrative only, since numerousmodifications and variations therein will be apparent to those skilledin the art.

Composition A

The following materials were added in the order and manner described toa suitable reaction vessel equipped with an agitator, a fractionaldistillation column, a condenser, a distillation receiving vessel, anitrogen inlet, an internal temperature probe connected to an externalelectronic controller and a heating mantle:

Material Weight (grams) Charge-1 Trimethylolpropane 265.1Hexahydrophthalic anhydride 1225.3 Neopentyl glycol 435.92,2,4-trimethyl-1,3- 566.8 pentanediol Triphenyiphosphite 2.75 Butylstannoic acid 3.76 Charge-2 Triphenylphosphite 3.7 Butyl stannoic acid3.7 Charge-3 DOWANOL PM carbamate 2160.1 solution⁽¹⁾ Charge-4 DOWANOLPM⁽²⁾ 876.3 ⁽¹⁾Reaction product of DOWANOL PM and urea as a 38 weightpercent solution in Dowanol PM. ⁽²⁾1-methoxy-2-propanol available fromDow Chemical Co.

Charge 1 was added to the reaction vessel. Nitrogen was introduced toblanket the reactants and the agitator was turned on. After heating thereaction mixture to 80° C., nitrogen was sparged into the reactionmixture which was held at this temperature for 20 minutes. Heating wasresumed with continued nitrogen sparging until a reaction temperature of200°-210° C. was attained. The reaction was held in this temperaturerange while distilling off water until an acid value of 10.5 wasattained. The temperature of the reaction mixture was reduced to 140° C.and the fractional column was removed. The overhead equipment of thesystem was reconfigured for simple vacuum distillation and an additionfunnel was added to the reactor. Charge 2 was added to the reactionmixture. Charge 3 was added to the reaction vessel through the additionfunnel over a period of 4 hours.

During the addition of Charge 3, reduced pressure was maintained on thesystem to distill DOWANOL PM from the reaction mixture. After Charge 3was completed, distillation was maintained by gradually reducing thepressure inside the reaction vessel until a pressure of 60 mm Hg wasattained. The reaction mixture was held at this pressure untildistillation stopped. A sample was collected and had a measured hydroxylvalue of 8.2.

Charge 4 was added to the reaction mixture. The resulting polymersolution had a measured total solids content based on total solutionweight of 72.8 percent, a viscosity of on the Gardner-Holt viscosityscale, a weight average molecular weight of 2288 and a number averagemolecular weight of 1228 as determined by gel permeation chromatographyusing a polystyrene standard.

Composition B Part A

The following materials were added in the order and manner described toa suitable reaction vessel equipped with an agitator, a reflux column,addition vessels, nitrogen inlet, an internal temperature probeconnected to an external electronic controller and a heating jacket:

Material Weight (parts) Charge-1 DOWANOL PM solvent 192.6 Charge-2 Butylmethacrylate 1827.4 Hydroxypropyl acrylate 1260.2 Methyl styrene dimer63.0 Charge-3 DOWANOL PM solvent 85.8 LUPEROX 575 initiator⁽³⁾ 110.3Charge-4 DOWANOL PM solvent 30.0 Charge-5 DOWANOL PM solvent 31.6LUPEROX 575 initiator 31.6 Charge-6 DOWANOL PM solvent 20.0

Part B

The following materials were added in the order and manner described toa suitable vessel equipped with an agitator.

Material Weight (parts) Charge-1 DOWANOL PM carbamate solution 2836.2DOWANOL PM 15.0 Charge-2 All of the reaction product of Part A. Charge-3Triphenylphosphite 9.6 Butyl stannoic acid 2.4 DOWANOL PM 10.0 Charge-4DOWANOL PM solvent 925.0 Ethyl 3-ethoxypropionate 950.0 ⁽³⁾t-amylperoxy-2-ethylhexanoate available from Elf Atochem North America, Inc.

Charge 1 of Part A was added to the reaction vessel. The vessel waspurged with a mixture of 95:5 nitrogen/oxygen and the agitator wasturned on. The reaction vessel was sealed and the internal pressure wasreduced to 240 mm Hg. Heat was applied to the reaction vessel until atemperature of 165° C. was reached. Charges 2 and 3 were addedseparately to the reaction vessel in a continuous manner over a periodof 180 and 188 minutes respectively. The addition of Charge 3 wasstarted 8 minutes before the addition of Charge 2. Two hours afterstarting the addition of Charge 3, the temperature of the reactionmixture was reduced from 165° to 149° C. over a 60 minute period. WhenCharges 2 and 3 were completed, Charge 4 was added to the reactionmixture as a rinse for Charge 2 and the pressure on the reactor wasslowly relieved. When the temperature was still above 140° C., Charge 5was added over 1 hour. Charge 6 was added to the reaction mixture as arinse for Charge 5. The reaction mixture was held at a temperature above140° C. for an additional 1 hour while mixing.

Charge 1 of Part B was added to a suitable second vessel. Charge 2 wasadded. Charge 3 was added and the mixture was stirred. The resultingmixture was transferred to the reactor of Part A over a period of 7.3hours. During the transfer, the temperature of the reactor was keptbetween 131° and 139° C. Reduced pressure was also maintained in thereaction vessel to ensure steady distillation of DOWANBL PM from thereaction mixture. After the transfer was completed, the pressure in thereaction vessel was gradually reduced to maintain distillation until afinal pressure of 41 mm Hg was attained. When the distillation stopped,a sample was collected and the measured hydroxyl value was 40.8.

Charge 4 was added with mixing to the contents in the reactor. Theresulting polymer solution had a measured total solids content, based ontotal solution weight, of 63.0 percent, a viscosity of Z minus on theGardner-Holt viscosity scale, and a weight average molecular weight of9107 and a number average molecular weight of 3645 as determined by gelpermeation chromatography using a polystyrene standard.

Composition C

The following materials were added in the order and manner described toa suitable reaction vessel equipped with an agitator, a reflux column,an addition funnel, nitrogen inlet, an internal temperature probeconnected to an external electronic controller and a heating mantle:

Material Weight (grams) Charge-1 SOLVESSO 100 solvent⁽⁴⁾ 22.8 Xylene22.8 Isobutanol 10.9 Charge-2 Butyl acrylate 20.4 Styrene 51.1Ethylimidazolidonemethacrylate 40.9 Methyl methacrylate 163.4 Charge-3Xylene 21.9 SOLVESSO 100 solvent 16.4 VAZO-67 initiator⁽⁵⁾ 12.8 Charge-4SOLVESSO 100 solvent 14.6 VAZO-67 initiator 2.04 ⁽⁴⁾Aromatic solventavailable from Exxon. ⁽⁵⁾2,2′-Azobis-(2-methylbutyronitrile) availablefrom E.I. duPont de Nemours and Company.

Charge-1 was added to the reaction vessel. Nitrogen was introduced intothe vessel with the agitator running and heat was applied to the reaction vessel to maintain a temperature at which reflux of the solventoccurred. After reaching the reflux temperature, Charges-2 and -3 wereadded separately to the reaction vessel in a continuous manner over aperiod of 2 hours. Subsequently, Charge-4 was added over half an hourand the reaction mixture was held an additional 1.5 hours at the refluxtemperature. The contents of the reaction vessel were then cooled andtransferred to a suitable container The resulting polymer solution had acalculated total solids content, based on total solution weight, ofabout 77.9 percent. The polymer had a urea equivalent weight of about1308 based on polymer solids.

Composition D

The following materials were added in the order and manner described toa suitable reaction vessel equipped with an agitator, a reflux column,an addition funnel, nitrogen inlet, an internal temperature probeconnected to an external electronic controller and a heating mantle:

Material Weight (grams) Charge-1 SOLVESSO 100 solvent 47.4 Xylene 22.8Isobutanol 47.4 Charge-2 Hydroxypropyl acrylate 159.3 Butyl acrylate100.9 Butyl methacrylate 58.4 Styrene 106.2Ethylimidazolidonemethacrylate 21.2 Methyl methacrylate 95.6 Methylmethacrylate 5.6 Charge-3 Xylene 45.5 SOLVESSO 100 solvent 34.1 VAZO-67initiator 26.5 Charge-4 SOLVESSO 100 solvent 30.3 VAZO-67 initiator 4.25

Charge-1 was added to the reaction vessel. Nitrogen was introduced intothe vessel with the agitator running and heat was applied to thereaction vessel to maintain a temperature at which reflux of the solventoccurred. After reaching the reflux temperature, Charges-2 and -3 wereadded separately to the reaction vessel in a continuous manner over aperiod of 2 hours. Subsequently, Charge-4 was added over half an hourand the reaction mixture was held an additional 1.5 hours at the refluxtemperature. The contents of the reaction vessel were then cooled andtransferred to a suitable container. The resulting polymer solution hada calculated total solids content, based on total solution weight ofabout 71.6 percent. The polymer had a weight average molecular weight,as measured by gel permeation chromatography using polystyrene as astandard, of about 13,000, urea equivalent weight of about 5,240, andhydroxy equivalent weight of 1099 based on polymer solids.

Composition E

The following materials were added in the order described to a suitablevessel.

Material Weight (grams) Photochromic 1⁽⁶⁾ 6.75 TINUVIN ® 144 UVstabilizer⁽⁷⁾ 1.69 BAYSILONE ® PL paint additive⁽⁸⁾ 0.063 pTSA⁽⁹⁾ 2.25CYMEL ® 350 resin⁽¹⁰⁾ 30.75 NMP⁽¹¹⁾ 30.28 ⁽⁶⁾A naphtho[1,2-b]pyran thatexhibits a blue color when irradiated with ultraviolet light.⁽⁷⁾Hindered amine ultraviolet light stabilizer available from CIBA-GEIGYCORPORATION. ⁽⁸⁾Phenyl methyl polysiloxane available from BayerCorporation. ⁽⁹⁾para-Toluene sulfonic acid. ⁽¹⁰⁾Described as a highlymethylated, monomeric melamine formaldehyde resin available from CytecIndustries, Inc. ⁽¹¹⁾N-methyl pyrrolidone solvent of 99 percent purity.

After all of the materials were added to the vessel, the contents wereheated for about 15 minutes at 60° C.

Composition F

The procedure used to prepare Composition E was followed except thatpTSA was not used. The same amounts of the other materials inComposition E were used.

Composition G

The following materials were added in the order described to a suitablevessel.

Material Weight (grams) Photochromic 1 13.5 TINUVIN ® 144 UV stabilizer3.38 BAYSILONE ® PL paint additive 0.12 CYMEL ® 350 resin 37.75 NMP79.03

After all of the materials were added to the vessel, the contents wereheated for about 15 minutes at 60° C.

Composition H

The procedure used to prepare Composition G was followed except thatpTSA, 1.22 grams, was added. The same amounts of the other materials inComposition G were used.

EXAMPLE 1

The following materials were added in the order described to a suitablevessel.

Material Weight (grams) Composition A 2.85 pTHF⁽¹²⁾ 1.36 Composition E4.67 ⁽¹²⁾poly(oxytetramethylene)diol having a number average molecularweight of 1000 which is available from Great Lakes Chemical Corporation.

After all of the materials were added to the vessel, the contents weremixed at 5000 revolutions per minute (rpm) for about 2 minutes, ifnecessary, to obtain a clear solution.

EXAMPLE 2

The procedure of Example 1 was followed except that 2.38 grams ofComposition A was used and 1.7 grams of pTHF was used. The same amountsof the other materials in the composition of Example 1 were used.

EXAMPLE 3

The procedure of Example 1 was followed except that 3.86 grams ofComposition B was used in place of Composition A and 1.02 grams of pTHFwas used. The same amounts of the other materials in the composition ofExample 1 were used.

EXAMPLE 4

The procedure for Example 3 was followed except that 3.31 grams ofComposition B and 1.36 grams of pTHF were used.

EXAMPLE 5

The procedure for Example 3 was followed except that 2.76 grams ofComposition B and 1.7 grams of pTHF were used.

EXAMPLE 6

The following materials were added in the order described to a suitablevessel.

Material Weight (grams) Composition C 3.95 pTHF 0.34 Composition G 5.35

After all of the materials were added to the vessel, the contents weremixed at 5000 rpm for about 2 minutes, if necessary, to obtain a clearsolution.

EXAMPLE 7

The procedure of Example 6 was followed except that 5.40 grams ofComposition H was used in place of Composition F, and 3.07 grams ofComposition C and 1.02 grams of pTHF were used.

EXAMPLE 8

The procedure of Example 7 was followed except that 2.63 grams ofComposition C and 1.36 grams of pTHF were used.

EXAMPLE 9

The procedure of Example 6 was followed except that 4.77 grams ofComposition D was used in place of Composition C and no pTHF was used.The same amounts of the other materials in the composition of Example 6were used.

EXAMPLE 10

The procedure of Example 7 was followed except that 3.82 grams ofComposition D was used in place of Composition C and 0.68 gram of pTHFwas used. The same amounts of the other materials in the composition ofExample 7 were used.

EXAMPLE 11

The procedure of Example 10 was followed except that 3.34 grams ofComposition D and 1.02 grams of pTHF were used.

Comparative Example 1

The procedure of Example 1 was followed except that 3.33 grams ofComposition A was used and 1.2 grams of pTHF was used. The same amountsof the other materials in the composition of Example 1 were used.

Comparative Example 2

The procedure of Example 1 was followed except that 1.9 grams ofComposition A was used and 2.04 grams of pTHF was used. The same amountsof the other materials in the composition of Example 1 were used.

Comparative Example 3

The procedure of Example 3 was followed except that 4.41 grams ofComposition B and 0.68 grams of pTHF were used. The same amounts of theother materials in the composition of Example 3 were used.

Comparative Example 4

The procedure of Example 3 was followed except that 2.20 grams ofComposition B and 2.04 grams of pTHF were used. The same amounts of theother materials in the composition of Example 3 were used.

Comparative Example 5

The procedure of Example 6 was followed except that 4.39 grams ofComposition C was used and no pTHF was used. The same amounts of theother materials in the composition of Example 6 were used.

Comparative Example 6

The procedure of Example 6 was followed except that 3.51 grams ofComposition C and 0.68 grams of pTHF were used.

Comparative Example 7

The procedure of Example 7 was followed except that 3.51 grams ofComposition C and 0.68 grams of pTHF were used.

Comparative Example 8

The procedure of Example 7 was followed except that 2.2 grams ofComposition C and 1.7 grams of pTHF were used.

Comparative Example 9

The procedure of Example 9 was followed except that 4.29 grams ofComposition D and 0.34 gram of pTHF were used.

Comparative Example 10

The procedure of Example 10 was followed except that 4.29 grams ofComposition D and 0.34 gram of pTHF were used.

Comparative Example 11

The procedure of Example 10 was followed except that 2.86 grams ofComposition D and 1.36 grams of pTHF were used.

EXAMPLE 12 Part A

The solutions prepared in Examples 1-11 and Comparative Examples 1-11were applied via a spincoating method to lens blanks made of CR-39®monomer. Prior to application of the coating, each lens blank was washedwith detergent, rinsed with water, immersed for 3 minutes in an aqueouspotassium hydroxide solution having a normality of about 2.4 which wasmaintained at about 50° C. and then rinsed twice with deionized water.The immersion and subsequent rinsing steps were conducted in a BramsonUltrasonic Model 5200 Sonnicater. The solutions were dispensed onto eachlens which was spinning at 2000 rpm. The lenses coated with solutions ofthe Examples and Comparative Examples were cured for 40 minutes in aconvection oven maintained at 140° C.

Part B

The photochromic coated test lenses prepared in Part A were subjected tomicrohardness (F_(h)) testing using a Fischerscope HCV, Model H-100available from Fischer Technology, Inc. The microhardness, measured inNewtons (N) per mm², of the coated test samples was determined by taking3 measurements at a depth of 2 microns in the center area of the testsample prepared for each Example under the conditions of a 100milliNewton load, 30 load steps and 0.5 second,pauses between loadsteps. Prior to testing, each lens was stored in an enclosed chamberhaving a humidity of not more than 50 percent, e.g., 30 percent, for atleast 12 hours. The test results are listed in Table 1.

Part C

The photochromic coated test lenses from Part B were placed in a SiemensPE-1000 AC Plasma unit. The lenses were treated with oxygen plasma underthe following conditions: power was set to 100 Watts; gas pressure was38 pascals; a gas flowrate of 100 mL/minute was used; and the processingtime was 60 seconds.

The plasma treated lenses were coated with HiGard® 1030 coating solutionvia a spincoating method. Approximately 4 mL of HiGard® 1030 coatingsolution was dispensed onto each lens which was spinning at 1100revolutions per minute (rpm) for 13 seconds. Afterwards, the lenses wereheated in a 60° C. oven for 20 minutes and then in a 120° C. oven for 3hours.

Part D

The photochromic coated test lenses prepared in Part C were tested forphotochromic response on an optical bench in the 85° F. PhotochromicPerformance Test described hereinafter. Prior to testing on the opticalbench, the photochromic test samples were exposed to 365 nanometerultraviolet light for about 20 minutes to activate the photochromiccompounds and then placed in a 75° C. oven for about 20 minutes tobleach (inactivate) the photochromic compounds. The coated test sampleswere then cooled to room temperature, exposed to fluorescent roomlighting for at least 2 hours and then kept covered for at least 2 hoursprior to testing on an optical bench. The bench was fitted with a 300watt Xenon arc lamp, a remote controlled shutter, a Schott 3 mm KG-2band-pass filter, which removes short wavelength radiation, neutraldensity filter(s), a quartz cell sample holder for maintaining sampletemperature in which the test sample to be tested was inserted.

The power output of the optical bench, i.e., the dosage of light thatthe test sample would be exposed to, was adjusted to 0.67 milliwatts persquare centimeter (mW/cm²) using a GRASEBY Optronics Model S-371portable photometer (Serial #21536) with a UV-A detector (Serial#22411). The UV-A detector was placed into the sample holder and thelight output was measured. Adjustments to the power output were made byincreasing or decreasing the lamp wattage or by adding or removingneutral density filters in the light path.

A monitoring, collimated beam of light from a tungsten lamp was passedthrough the sample at 30° normal to the surface of the lens. Afterpassing through the lens, the light from the tungsten lamp was directedthrough a 570 nanometer (nm) filter attached to a detector. The 570 nmfilter passes wavelengths characteristic of the photochromic compoundused in the examples. The output signals from the detector wereprocessed by a radiometer. The control of the test conditions andacquisition of data was handled by the Labtech Notebook Pro software andthe recommended I/O board.

Change in optical density (ΔOD) from the bleached state to the darkenedstate was determined by establishing the initial transmittance, openingthe shutter from the Xenon lamp to provide ultraviolet radiation tochange the test sample from the bleached state to an activated (i.e.,darkened) state at selected intervals of time, measuring thetransmittance in the activated state, and calculating the change inoptical density according to the formula: ΔOD=log(%Tb/%Ta), where %Tb isthe percent transmittance in the bleached state, %Ta is the percenttransmittance in the activated state and the logarithm is to the base10.

The ΔOD was measured using a 570 nanometer filter after the first thirty(30) seconds of UV exposure and then after eight (8) minutes with theoptical bench maintained at a temperature of 85° F. (29.4° C.). TheBleach Rate (T 1/2) is the time interval in seconds for the ΔOD of theactivated form of the photochromic compound in the coated test samplesto reach one half the highest ΔCOD at (85° F., 29.4° C.) after removalof the source of activating light. Results for the photochromic coatedtest samples for each Example and Comparative Example are listed inTable 2.

TABLE 1 Fischer Microhardness Example No. Newtons/mm² 1 110 2 71 3 118 485 5 65 6 83 7 113 8 50 9 62 10 114 11 64 CE1 153 CE2 36 CE3 149 CE4 31CE5 214 CE6 36 CE7 163 CE8 9 CE9 10 CE10 169 CE11 25

TABLE 2 ΔOD @ 85° F. ΔOD @ 85° F. T 1/2 Example No. After 30 sec. After8 min. seconds 1 0.18 0.49 125 2 0.28 0.61 84 3 0.23 0.56 140 4 0.310.63 87 5 0.38 0.69 64 6 0.23 0.72 98 7 0.24 0.60 96 8 0.38 0.71 56 90.38 1.26 173 10 0.26 0.66 99 11 0.36 0.69 64 CE1 0.12 0.37 201 CE2 0.380.71 59 CE3 0.16 0.48 239 CE4 0.45 0.73 45 CE5 0.07 0.47 479 CE6 0.210.38 64 CE7 0.13 0.44 184 CE8 0.45 0.73 44 CE9 0.5o 0.70 36 CE10 0.120.48 >500 CE11 0.46 0.73 39

The results of Table 1 and 2 show that the lenses coated with thesolutions of Examples 1 through 11 had the following properties:microhardness results that were within the desired range from 45 to 180Newtons/mm²; a ΔOD of at least 0.15 after 30 seconds and at least 0.47after 8 minutes; and a fade rate of not more than 180 seconds, alltested at 85° F. (29.4° C.). All of the lenses coated with the solutionsof the Comparative Examples had a result for at least one of theaforementioned properties that was outside of the desired range.

Although the present invention has been described with reference tospecific details of certain embodiments thereof, it is not intended thatsuch details should be regarded as limitations upon the scope of theinvention except insofar as they are included in the accompanyingclaims.

We claim:
 1. An article comprising, in combination, a substrate and acured aminoplast resin coating containing photochromic compound(s) on atleast one surface of said substrate, said photochromic aminoplast resincoating being prepared from a coating composition comprising: (a) areaction product of (i) functional component(s) having groups reactivewith aminoplast crosslinking agents selected from: (A) hydroxyl; (B)carbamate represented by the following structures:

 wherein A is —C— or —O—; R is hydrogen or C₁-C₁₈ alkyl, or R is bondedto A and forms part of a 5 or 6 membered ring; R′ is a C₁-C₁₈ alkyl; (C)urea represented by the following structure:

 wherein B is —NH—, R″ is hydrogen or C₁-C₁₈ alkyl, or R″ is bonded to Band forms part of a 5 or 6 membered ring; or (D) a mixture therof;provided that said functional component (a)(i) provides at least twodifferent reactive groups selected from (A), (B), or (C); and (ii)aminoplast crosslinking agent having at least two reactive groups; and(b) a photochromic amount of photochromic compounds(s); said components(a)(i), (a)(ii) and (b) being used in such proprotions to produce acured coating exhibiting a Fischer microhardness of from at least 45 tonot more than 180 Newtons per mm², and photochromic propertiescharacterized by a ΔOD of at least 0.15 after 30 seconds and at least0.47 after 8 minutes, and a bleach rate of not more than 180 seconds—allas measured in the 85° F. Photochromic Performance Test.
 2. The articleof claim 1 wherein the cured coating exhibits a Fischer microhardness offrom at least 55 to not more than 160 Newtons per mm², a ΔOD of at least0.16 after 30 seconds and at least 0.50 after 8 minutes, and a bleachrate of not more than 140 seconds.
 3. The article of claim 2 wherein thecured coating exhibits a Fischer microhardness of from at least 60 tonot more than 150 Newtons per mm², a ΔOD of at least 0.17 after 30seconds and at least 0.55 after 8 minutes, and a bleach rate of not morethan 100 seconds.
 4. The article of claim 1 wherein the photochromicaminoplast resin coating further comprises a catalytic amount ofcatalyst for accelerating the curing reaction between the reactivegroups of (a)(i) and the aminoplast reactive groups of (a)(ii).
 5. Thearticle of claim 4 wherein the catalyst is selected from phosphoricacid, substituted phosphoric acid, sulfonic acid, substituted sulfonicacid or a mixture thereof.
 6. The article of claim 1 wherein the ratioof equivalents of the reactive groups (a)(i) to aminoplast reactivegroups (a)(ii) ranges from 0.5 to 2.0:1.
 7. The article of claim 1wherein the functional component(s) (a)(i) have reactive groups selectedfrom: (a) hydroxyl; (b) carbamate represented by the followingstructure:

wherein A is —C— or —O—; and R is hydrogen or C₁-C₆ alkyl; or (c) amixture thereof.
 8. The article of claim 1 wherein the functionalcomponent a)(i) is selected from polyacrylic polymers, polyesterpolymers, polyurethane polymers, organic polyols or a mixture thereof.9. The article of claim 1 wherein the functional component havinghydroxyl groups is selected from polyacrylic polyols, polyether polyolsor a mixture thereof.
 10. The article of claim 9 wherein the polyacrylicpolyol is a co-polymer of ethylenically unsaturated monomer(s) having atleast two hydroxyl groups and at least one polymerizable ethylenicallyunsaturated monomer which is free of hydroxyl groups.
 11. The article ofclaim 1 wherein the aminoplast crosslinking agent is a condensate ofmelamine with formaldehyde and optionally an alcohol containing from 1to 6 carbon atoms.
 12. The article of claim 11 wherein the aminoplastcrosslinking agent is a condensation product of melamine withformaldehyde and an alcohol containing from 1 to 4 carbon atoms.
 13. Thearticle of claim 1 wherein the reactive groups of the aminoplastcrosslinking agent are selected from methylol, methylol ether groups, ora mixture thereof.
 14. The article of claim 1 wherein the photochromiccompound(s) comprise: (a) at least one photochromic compound having avisible lambda max of from 400 nanometers to 525 nanometers; and (b) atleast one photochromic compound having a visible lambda max of fromgreater than 525 nanometers to 700 nanometers.
 15. The article of claim14 wherein the photochromic compound(s) are benzopyrans, naphthopyrans,phenanthropyrans, quinopyrans, indeno-fused naphthopyrans, benzoxazines,naphthoxazines, spiro(indoline)pyridobenzoxazines, metal-dithizonates,fulgides, fulgimides or mixtures thereof.
 16. The article of claim 1wherein the photochromic aminoplast resin coating has a thickness offrom 5 to 200 microns.
 17. The article of claim 16 wherein thephotochromic aminoplast resin coating has a thickness of from 10 to 40microns.
 18. The article of claim 1 wherein said substrate is paper,glass, ceramic, wood, masonry, textile, metal or polymeric organicmaterials.
 19. The article of claim 19 wherein the polymeric organicmaterial is a solid transparent polymer selected from the groupconsisting of poly(methyl methacrylate), poly(ethylene glycolbismethacrylate), poly(ethoxylated bisphenol A dimethacrylate),thermoplastic polycarbonate, poly(vinyl acetate), polyvinylbutyral,polyurethane, polythiourethanes, and polymers of members of the groupconsisting of diethylene glycol bis(allyl carbonate) monomers,diethylene glycol dimethacrylate monomers, ethoxylated phenolmethacrylate monomers, diisopropenyl benzene monomers, ethoxylatedtrimethylol propane triacrylate monomers and mixtures thereof.
 20. Thearticle of claim 19 wherein said substrate is an optical element. 21.The article of claim 20 wherein said optical element is a lens.
 22. Thearticle of claim 21 wherein the refractive index of said lens is from1.48 to 2.00.
 23. A photochromic article comprising a polymerizate of apolymerizable composition comprising: (a) a reaction product of: (i)functional component(s) having groups reactive with aminoplastcrosslinking agents selected from: (A) hydroxyl; (B) carbamaterepresented by the following structures:

 wherein A is —C— or —O—; R is hydrogen or C₁-C₁₈ alkyl, or R is bondedto A and forms part of a 5 or 6 membered ring; R′ is a C₁-C₁₈ alkyl; (C)urea represented by the following structure:

 wherein B is —NH—, R″ is hydrogen or C₁-C₁₈ alkyl, or R″ is bonded to Band forms part of a 5 or 6 membered ring; or (D) a mixture thereof;provided that said functional component (a)(i) provides at least twodifferent reactive groups selected from (A), (B), or (C); and (ii)aminoplast crosslinking agent having at least two reactive groups; and(b) a photochromic amount of photochromic compound(s), said components(a)(i), (a)(ii) and (b) being used in such proportions to produce apolymerizate exhibiting a Fischer microhardness of from at least 45 tonot more than 180 Newtons per mm2, and photochromic propertiescharacterized by a ΔOD of at least 0.15 after 30 seconds and at least0.47 after 8 minutes, and a bleach rate of not more than 180 seconds—allas measured in the 85° F. Photochromic Performance Test.
 24. Thephotochromic article of claim 23 wherein said polymerizable compositionfurther comprises a catalytic amount of catalyst.
 25. The article ofclaim 23 wherein the reactive groups of the aminoplast resin areselected from methylol, methylol ether groups, or combinations thereof.26. The photochromic article of claim 23 wherein said article is a lens.27. The photochromic article of claim 26 wherein said lens has athickness of at least 0.5 millimeters.